284 PROTOPLASM WALLS OF CAPILLARIES 



llzation, and anatomical elements (cells) were supposed 

 to be deposited from an albuminous solution (cell stuff), 

 just as a crystal is deposited from its mother liquor. 

 Of late, however, very different conclusions have been 

 arrived at, and accepted even by those who still 

 adhere to the doctrines of purely physical physiology. 

 It has long been admitted that capillary vessels possess 

 " nuclei," though the ofiB.ce performed by these bodies 

 had not been conclusively determined. Some thought 

 the nuclei belonged to an epithelium Uiiing the capil- 

 lary vessels, but every one who studied the formation 

 of capillaries must have satisfied himself at any rate 

 that these " nuclei " bore the same relation to the 

 tissue of the capillary wall as the "nuclei " of other 

 tissues bore to the particular textui'e in which they 

 were embedded. In 1865, however, Hozier. Auer- 

 bach, Eberth, Aeby, and Chrzonszczewsky,* by means 

 of nitrate of silver, showed that the capillary wall was 

 made up of flat elongated epithelium-like particles, 

 much dentated at the margins, and each having a 

 nucleus. The nitrate of silver gave rise to a black 

 line at the point of junction of the several particles, 

 and this fact led observers to conclude that the vessel 

 was made of epithelial cells. 



Between these particles some think they have 

 demonstrated the openings through which, according 

 to their opinion, red and white blood corpuscles might 

 escape from the vessels. It was well known that 

 blood coipjuscles did, under certain cii'cumstances, 

 pass through the vascular walls. It was argued that 

 such bodies could escape only through actual orifices, 

 and the discovery of the stomata through which it 

 was concluded they did pass, soon followed. 



395. Protoiilasm walls of capillaries. — But lately, 

 the matter has entered yet another phase. We are 



* See E berth's Article, "Blood-vessels," Strieker's Anatomy, 

 New Sydenham Society. 



